The study shows a novel, hybrid concept of a constructed wetland for the first time in a
water-stressed region in the coldest capital in the world, Ulaanbaatar, Mongolia. This system was based on storing water during the winter freezing period as an ice block, and then starting treatment during the summer/non-freezing period. Results showed that the maximum removal rates of chemical oxygen demand, ammonia, nitrite, total suspended solids, phosphorus,and Escherichia coli were up to 100%, 99%,97%, 97%, 87%, and 98%, respectively. The effluent met the neighbouring country, China's, municipal discharge standard of A grade effluent and could also be considered restricted and unrestricted irrigation water as reported in other studies. The system has proven potential from a technical point of view and can be scaled up to community or cluster levels. This would enable reduction of greywater-borne hazards in low, middle and high income countries with similar contexts.